In certain applications, corrosive or abrasive fluids (for example, oil well drilling fluid, commonly known as "mud") must be pumped. Many of the pumps used for this application have special liners through which the mud is pumped, and, after being used for some time, the liner wears and needs to be replaced. Unfortunately, the liner must serve many purposes. First, the liner must be hard to resist the abrasive nature of the fluids that move through the liner. Second, the liner must be machinable to fit the close tolerances required of the pumps. Hard, abrasive-resistant materials are not very machinable. Also, the pressures and forces that act on the liner are extreme, and the liner can be very large. Therefore, there is a desire to use inexpensive materials in the construction of the liner. Unfortunately, most inexpensive materials are not abrasive or corrosive-resistant.
Attempts to address these issues have been made, but industry has settled on a dual-metal liner having an abrasive and corrosive-resistant inner surface and a machinable outer surface. One such liner is centrifugally cast, wherein a carbon steel outer shell is cast in a spinning mold, and a high-chrome steel is then poured into the interior of a hot outer shell. Upon cooling, the result is a metallurgical bond between the inner sleeve and outer shell, and the liner has a hard inner surface and a machinable outer surface. However, critical spinning speeds, pour temperatures, and other parameters, make such a liner and process very expensive and difficult to make.
Another method of making the liner is to shrink fit, wherein the carbon steel shell is heated and the high-chrome sleeve is cooled. The two are then press-fit together. Upon reaching a common temperature, the sleeve has expanded and the shell has shrunk, thus creating a tight fit. However, there is no metallurgical seal between the two.
Attempts have been made at static casting the steel shell and the sleeve. However, this method was abandoned as a failure, because the brittle sleeve would crack.
Thus, there is a need for a liner that is inexpensive, corrosive-resistant, and abrasive-resistant on the inner surface, while being machinable on the outer surface. Also, there is a need for an inexpensive method of making such a liner.